Uzu for iPad is endlessly complicated, simply fun

Uzu for iPad is an interactive visualizer that will no doubt entertain you for …

iPad app Uzu, Japanese for Vortex, is described by the developer as a “kinetic multitouch particle visualizer." While that may sound complicated, it can be broken down fairly simply: you touch your iPad’s screen and it looks awesome. Inspired by childhood trips to the Museum of Science and Industry in Chicago, developer Jason Smith's application attempts to bring the same amount of awe and amusement as one of those interactive plasma globes that were once a novelty, but can now be found at every remaining Spencer’s Gifts. Kids, adults, the mind-altered, and just about everyone else will get at least few minutes of enjoyment. Put simply, Uzu is interactive art.

In talking to Smith, I felt what I imagine the kindergartners at Springfield Elementary School on The Simpsons felt when Professor Frink became the substitute teacher during the teachers' strike. They wanted to understand how the tiny plastic balls shot around the toy vacuum cleaner as it zoomed around the room, but, alas, Frink’s diagrams and explanations were too much for them to comprehend. I came out of my talk with Smith understanding more or less a fragment of what we talked about, but like the aforementioned kindergartners, I knew that in the end, despite my lack of comprehension, that toy vacuum was fun.

Uzu reacts to touches to the screen, and can handle up to 10 instances at any given time. If nothing capable of capacitance is making contact with the screen, green, red, and yellow particles float around in a Brownian motion-inspired dance. By my calculations, at any one time there can be up to 2.25 million calculations taking place. Each particle on screen has 25 properties attached to it, including—but not limited to—position, velocity, acceleration, RGB color, HSV color, and a number of different oscillators. Smith says the “sweet spot” seems to be 3,000 particles on the screen at any given time.

An individual particle can range in size from one to 20 pixels in width. Each particle is tracked and maintained by Open GL ES. The number of digits touching the screen determines how particles interact with their environment. The intention being, the more fingers touching the screen, the more intense the particle dance becomes. Particles all reside on the same plane, and can occupy the same space at any given time. There is no particle collision detection; in a few of the modes (what the programmer refers to as “modes” are actually the interactions between particles triggered by varying amounts of fingers), there is border collision direction.

When a single finger is touching the iPad’s multitouch screen, three things happen: particles wander around in the Brownian manner mentioned earlier, they move away from the single finger, and when they reach the edge of the device they are transported to the location of the finger where they are immediately shot out towards the edges of the device. When the finger is dragged, the same effect happens, but particles are shot out in the opposite direction that the finger is traveling in.

If a user applies five fingers to the screen, motion stops and the particles begin “twinkling," and a sort of particle ball forms, which shrinks over time. The real fun comes from moving fingers around the device, picking them up and adding them as you go. The effect transitions are instantaneous, so the application can be quite mesmerizing. Descriptions such as tri-point vortex, 3D solid oscillating mass, 3D warp, and inverted translate only go so far, so check out the video below to see the application in action.

It’s all quite complicated with the ratios, particle energy, and so on. It’s clear that this is a labor of love for Smith. The application is inspired by his readings of quantum physics and string theory, and his boyhood aspirations to be an astronomer. Smith quit his full time job where he was lead developer at Colossal Squid Industries in Chicago, and moved to New York to start a life as an indie developer for iOS. Prior to Uzu, with the exception of a few tutorials, he had no prior iOS experience; in the past he had been doing primarily heavy Actionscript 3 work in Eclipse. iOS and Objective C weren’t to hard to learn, with most of his issues stemming from syntax across languages; OpenGL, however, was difficult for him to pick up. Smith cites a steep learning curve as the primary reason for that.

Despite the complexity, Uzu is fun, giving you the feeling of conducting a symphony of particles. It might have limited functionality, but it will give you at least 99¢ of entertainment, the current cost of the application. Jason has big ideas for Uzu, including plans to make it more interactive. I'm excited to see what he comes up with, even if I don’t entirely understand it.

24 Reader Comments

Pointless because you're not doing anything other than creating fleeting patterns on the screen, and a complete waste of time because the darned thing is so mesmerising that you'll run your iPad's battery down before you stop playing with it.

I've got both, and I can't imagine Uzu working half as well on the iPhone without a serious redesign. Some of the most interesting interactions happen around 6-8 fingers touching the screen, and at that level you'd be really struggling to actually see the screen. Also, the larger range of movements on the iPad coupled with the sensitivity of the sensors make it quite fun to have groups of fingers a long way apart, moving very slightly and tweaking the patterns that are formed.